Vitamin D and respiratory health in the Busselton Healthy Ageing Study

BACKGROUND AND OBJECTIVE: The relationship between vitamin D and respiratory disease was examined by cross-sectional analysis of a large community-based sample. METHODS: Serum 25-hydroxyvitamin D (25OHD) and history of respiratory disease, symptoms (recorded by questionnaire) and spirometry were measured in 5011 adults aged 45-69 years. Adjustments were made for age, sex, season and smoking (Model A), plus body mass index (BMI) and physical activity level (Model B), plus history of chronic diseases (Model C). RESULTS: Mean (SD) age was 58 (SD 6) years with 45% males, 10% current smokers and 12% taking vitamin D supplements. The prevalence of 25OHD level  100 nmol/L had higher forced vital capacity (FVC) in all the three models (1.17% higher, compared with the 50-100 nmol/L group in Model C). CONCLUSION: Low levels of serum 25OHD were independently associated with asthma, bronchitis, wheeze and chest tightness after three levels of adjustment for potential confounders. Higher vitamin D levels were associated with higher levels of lung function.